In my last post I mentioned some issues with the graphics utilities with Kyan Pascal, in this post I will review what I have found. The two issues I have run into is that stray pixels are plotted to the graphics screen with REAL number math code is executed and when text is written to the text part of the screen in a dual graphics and text screen mode.
Here is a graphics demo program to show these two issues. The program includes the GRAPHICS.I, PLOT.I and DRAWTO.I program extensions. The I wrote a simple procedure that draws a box on the graphics part the screen in graphics mode 7. After a short delay a two lines of code to initialize and add 0.1 to the REAL number variable R, another short delay then a WRITE to the text portion of the screen.
Here is what the screen looks like after the call to GRAPHICS(7) and drawing of the box, everything as expected :
After the short delay the two lines of code to initialize R to 1.00 and add 0.1, results in the follow changes to the screen, several stray pixels can now be seen:
and finally when the text ‘BOX DEMO’ is written to the screen, several more stray pixels are turned on. I did also test with only the writing of the text and the issues persists, so it’s not a residual from the math issue.
I am not sure of the cause of the issue, if it is specifically the library routines provided with Kyan Pascal, as I understand these were provided as additional utilities after the release of Kyan Pascal, but documentation seems to be scarce for these. Or perhaps there is an emulator issue? However I did test the same idea in BASIC and did not have an issue.
Heading into the last week of the RetroChallenge I hope to add the ability to load data from a text file and add that to the menu, and provide a final demo video on youtube.com.